1. Field of the Invention
The present invention relates to improvements in polymeric bags. Specifically, the present invention relates to polymeric bags utilizing a drawstring and typically used for trash or refuse disposal. Moreover, the present invention relates to polymeric bags utilizing both an elastic and inelastic drawstring in the same hem of the bag.
2. Description of the Related Art
Polymeric bags are ubiquitous in modern society. Polymeric bags can be manufactured using woven polymeric materials or manufactured using thin polymeric films with one or more material layers. Applications for which polymeric bags may be utilized are numerous with variations of polymeric bags used in a number of different industries. Moreover, some polymeric bags may exhibit certain properties depending on the specific polymeric materials used in the manufacturing process.
The present invention relates primarily to thin-film bags, typically polyethylene bags, used for trash or garbage collection. Such bags are typically manufactured using a blown-film extrusion process, providing a film material for the trash bag body which is subsequently converted into a final product. Polyethylene trash bags are available in different sizes, thicknesses, and colors and typically incorporate one of three different closure methods: straight top bags with twist tie closures; flapped bags where the flaps can be used to secure, tie, and carry the bag; and drawstring trash bags where a drawstring is provided within each hem to provide a method for securing, tying, and carrying the trash bags. The present invention is of particular relevance to drawtapes used in drawstring trash bags.
Over the past decade drawstring trash bags have enjoyed increasing commercial success as consumers recognize such bags increased utility. This is particularly true with respect to domestic household use where drawstring trash bags are now the most popular type of trash bags used in kitchen settings.
Such drawstring bags typically feature a drawstring located within each hem and anchored to the upper corners of the bag. The drawstrings can be used to pull the trash bag closed, to secure the trash bag mouth closed by tying the drawstrings closed, and to provide handles for carrying the closed, filled trash bag. Traditionally, such drawstrings were manufactured using primarily high density polyethylene, which offers increased tensile strength when compared to linear low density polyethylene or low density polyethylene. However, new improved drawstrings are emerging which provide other features and functions, particularly with respect to securing the top of the drawstring trash bag onto a trash receptacle.
One solution for gripping the top of a trash receptacle is described in U.S. Pat. No. 5,133,607 (the '607 patent) entitled “Plastic Liner Bag with Elastic Top Tie Strip.” The '607 Patent, which is incorporated herein by reference, describes using an elastic drawstring or band within the top of the drawstring bag. The elastic drawstring can be pulled outward at the top corners of the bag. Unfortunately, the elastic tie top requires relatively expensive elastomeric materials and a thicker gauge than traditional high density drawstrings.
Solutions have also been described for securing the top of the drawstring trash bag onto a trash receptacle using multiple drawtape elements. For instance, U.S. Pat. No. 6,164,824 (the '824 patent) entitled “Garbage Bag with Elastic Rim Edge Support,” describes an elastic loop with a rest diameter, the elastic loop located within an upper edge of a loop space of a trash bag. The elastic loop is pulled over an outer rim of a trash receptacle to a stretch diameter. The bag is described as being fixed to the garbage receptacle as the elastic element attempts to resume its rest diameter. The '824 patent also describes a loop shaped plastic cinch element located in the same upper edge of the loop space that may extend outside an opening of the upper edge of the loop space which may be used to tie the top end of the garbage bag. Both the cinch element and the elastic element are described as a continuous loop. The '824 patent discloses costly and difficult to manufacture materials for the cinch element, such as a band of fibrous material. The '824 patent also discloses relatively expensive and bulky materials for the elastic element, such as natural rubber, that is only capable of carrying a small fraction of the weight of a full trash bag.
Another solution involving multiple drawstring elements includes U.S. Pat. No. 6,585,415 (the '415 patent) entitled “Expandable Garbage Bag.” The '415 patent describes a drawstring garbage bag with inextensible ribbons disposed within hems at an upper opening of both sides of the bag. Further described is an elastic ribbon inserted into one of the two hems. Provided in at least the hem containing the elastic ribbon is a hole for accessing the ribbon. The elastic ribbon is configured so that it may be pulled out of the hem, once the bag has been placed in a container, and the hem wrapped over the top edge of the container, twisted, and wrapped around the outer circumference of the bag around the container to affix the bag to the container. The elastic ribbon requires a highly elastic material for stretching over the entire outer rim of a receptacle, adding considerable manufacturing costs to the garbage bag.
Another approach to improving drawstring trash bags is described in United States Published Patent Application No. 2011/0052103 (the '103 Application) entitled “Elastic Drawstring for Trash Bags,” assigned to Applicant and hereby incorporated into this disclosure by reference in its entirety. The '103 Application discloses a blend of linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE) to provide a drawstring with elastic-like properties. Specifically, when the two polyethylene resins are used together as described in the patent application, the resultant material provides limited elastic properties, with the blended drawtape exhibiting a greater percentage of elongation before yielding than either of the two materials would exhibit alone. Moreover, a 3 mil drawtape according to the '103 Application can provide elastic recovery of approximately 80%, which is greater than either the LLDPE or the LDPE materials would exhibit individually.
A further improvement to the blended LLDPE and LDPE drawstring of the '103 Application is described in United States Published Patent Application No. 2014/0254958 (the '958 Application) entitled “Cold-Stretched Drawstring Trash Bag”, assigned to Applicant and hereby incorporated by reference in its entirety into this disclosure. The '958 Application discloses a cold-stretch process applied to drawtape film that strain hardens the film, increasing the tensile strength at yield, and decreasing the elongation at yield of the film.
It would be advantageous to further improve the properties of the drawstring trash bag described in the '103 Application. For instance, it would be advantageous to improve the range of containers that a drawstring trash bag may be affixed to by using common polyethylene materials, such as high density polyethylene, linear low density polyethylene, and low density polyethylene. The above described '103 and '958 applications describe a bag that is capable of adhering to receptacle openings within a limited range. The below described invention provides a drawstring bag capable of easily adhering to a greater range of container openings while still being manufactured with the aforementioned common and low-cost polyethylene materials.